Google has been a big advocate of solar power and has been developing a smart tool which uses satellite imagery, 3D modelling and shade calculations from a combination of Google Earth and machine learning technology.
So far this has been available in North America (the USA and Puerto Rica) where it calculates the amount of energy a roof can develop and what the savings might be based on the local energy company figures.
To roll this out world wide, which is their plan, Google have made the API available for google developers to apply overlays and put in local data to provide local information.
For the UK at present any Project Sunroof will be available running in a limited way on energy companies websites.
BUT it is something for the future a FREE resource that will show the benefit of solar panels worldwide.